Container stock or the like



Jan. 22, 1946. N. P; 6033 ET AL CONTAINER STOCK OR THE LIKE Filed Aug. 8; 1941 Ferrous Bo se 0.! fa LUZ 3i INVENTORS Norman P. Cass i Erwin E. Bowen Palented .Fan. 22, was

CQNTAINER STOCK @B THE LEE Norman P, Goss, Youngstown, Ohio, and Erwin E, Bowen, Follansbee, W. Va, asdgnoro to The Cold Metal Process Company, Youngstown, Ohio, a corporation oil can Application August b, will, Serial No. coaooc l1 (Claim. (Ci. 29-381) This invention relates to sheet metaland, in particular, to that class of sheet metal produced for use as container stock, 1. e., thin sheet steel such as tin-plate.

The present standard specifications for. tinplate suited for container stool: require that the steel from which the tin-plate is rolled have a low carbon content, i. e., .10% to .12% and that it be substantially free from metalloids. It has been supposed heretofore that steel containing particularly adapted for use as container stock.

in a preferred embodiment, the sheet metal oi our invention includes a substantialamount of an alloying element, e. e., from 0.1% to 1% of silicon or the like. If appropriately cold-rolled, it is characterized sistauce to deformation-as well as a greater bendability or ability to withstand reverse bends, than ordinary cold-rolled tin-plate as now produced. The greater stiffness is indicated by the fact that under the so-called Schopper test (see A Bend Test for Tin Plate, by C. C. Willits, page 50, Metal Progress, Sept, 1936), our material, if properly cold rolled, exhibits a yield point of 40 kilograms per square millimeter or better. Its Eleater ductility is demonstrated by the fact that it can withstand from four to seven reverse bends over a sharp edge in a direction transverse to the direction of rolling.

The accompanying drawing is a section, considerably enlarged, through a piece or our improved sheet metal.

The material of our invention can be made with but little modification of present-day practlce. Steel of the desired silicon content may be easily produced in the open-hearth furnace and, when reduced to the form of billets, is readily converted into hot-rolled strip by known rolling methods. The hot-rolled strip is then pickled,

cold-rolled approximately to gauge and then subjected to the usual finishing operations such as normalizing or annealing, cleaning and the by a greater stiffness or resubstantial amounts of alloying elements such as and the bendability or container stock, whenproplike; and is then ready for the application ci a protective coating, e. e., tin, silver, lacquer, etc.

Before coating, the material is preferably given a heavy reduction, i. e., around 15%, in a temper pass, if the maximum stillness is desired. other wise the conventional temper-pass reduction of 3-5 may be efi'ected.

The material of our invention takes a uniform coating when subjected to the ordinary tinning process and is characterized by a firm bond between the base metal and the coating metal, an unusually bright finish, and the absence of can cessive [pin-hole porosity. The tinning of the base metal involves no special problems, contrary to the general supposition 1n the industry. The pin-hole porosity exhibited by the new material after tinning is not substantially greater than that or conventional tin-plate and it produces as good results as the latter in the hydrogen evolu tion test.

In the drawing, the ferrous base material is designated it and the protective coating, e. g, tin, isshown at M.

We have also discovered that similar small ad-= ditlons of alloying elements other than silicon, such as aluminum, copper and manganese, also produce an increase in the stifiness or yield point,

erly cold-rolled, without any substantial increase in porosity or hydrogen evolution, compared to the material now bein produced. The amount of such additions may be as high as 0.5% oi aluminum and up to 0.3% of the other elements.

From the foregoing, it will be apparent that our invention provides a novel type of sheet metal having important advantages over the container stock now used. Since the material of our in vention is stronger than present-day tin-plate, containers may now be made of stock thinner than that previously used, thereby efiectlng a substantial reduction in weight and saving in material, without impairing the resistance of the container to deformation. The increased bendability characterizing the new product, furthermore, is highly advantageous in container manufacture. The increase in 'stifiness oi the material resulting from skin-passing it to give a reduction up to 5% is much greater thanwould be expected in the case of steel containing silicon or the other alloying elements mentioned in the amounts stated.

Although we have disclosed but a preferred embodiment of the invention with certain modifications, it will be understood that variations may be made in thesheet metal disclosed witha yield point of at least 30 kilograms per square millimeter when subjected to the Schopper test and the ability to withstand at least 4 reverse bends over a sharp edge in a direction transverse to the direction of rolling, said stock being thereby particularly suitable for the manufacture of cans, because of its stiflness and bendabllity exceeding those of conventional tin-plate.

NORMAN P. GOES. ERWIN E. BOWEN. 

